Concentric lines and circuits therefor



June 4, 1940. P. D. ZOTTU 2,203,431

CONCENTRIC LINES AND CIRCUITS THEREFOR I Filed Jan. 21, 1937 4 Sheets-Sheet l DEN-070R mmm/cr AMPz/F/ER INVENTOR PAUL D. ZOTTU ATTORNEY June 4, 1940. P. D. ZOTTU CONCENTRIC LINES AND CIRCUITS THEREFOR Filed Jan. 21, 1957 4 Sheets-Sheet 2 INVENTOR PAUL D. ZOTTU BY 7+5 m ATTORNEY June 4, 1940. P. D. zo'r'ru 3, CDNCENTRIC LINES AND CIRCUITS THEREFOR Filed Jan. 21, 1937 4 SheetsSheet 5 INVENTOR PAUL D.ZOTTU ATTORNEY June 4, 1940. P. D. 20m, 2,203,431

CONCENTRIC LINES AND CIRCUITS THEREFOR Filed Jan. 21, 1957 4 Sheets-Sheet 4 INVENTOR PA U L D. ZOTTU BY 7/i/ww ATTORNEY Patented June 4, 1940 UNITED STATES PATENT OFFICE CONCENTRIC LINES AND CIRCUITS THEREFOR of Delaware Application January 21, 1937, Serial No. 121,500

28 Claims.

This invention relates to ultra-short radio wave apparatus, and particularly to tuned concentric lines and circuits for use in such apparatus.

One of the objects of the present invention is to provide a highly efficient short-wave radio receiver using tuned concentric lines, which receiver is compact and employs leads of minimum length between stages and their intermediate coupling elements.

Another object is to provide a novel type of concentric line and support therefor which enables adjustment of the effective length of the line, and movement of line and/or support with respect to each other and the associated equipment.

A further object is to provide a parallel arrangement of tuned concentric lines as coupling elements between stages, wherein the leads from the stages to the concentric lines can be tacked with ease onto any desired point along the length of the lines, whereby maximum sensitivity and maximum selectivity can be achieved.

A still further object is to provide a support and mounting for each electron discharge device of the receiver, which serves the dual purpose of a support adjustable in position with respect to the tuned concentric lines, and a by-pass condenser for the connecting leads.

A feature of the invention resides in the use of one or more slots along the length of the concentric line for enabling the inner conductor of the line to be coupled to an external circuit at any desired point along its length.

Another feature comprises a 'coiled or'spiraled 5 tuned concentric line for conserving space and enabling tapping of an external circuit to any point on the inner conductor.

A further feature lies in the use of a concentric line as a tuned circuit, the outer conductor of which is substantially U shaped and does not entirely surround the inner conductor.

Other objects, features and their advantages Will appear from a reading of the following description which is accompanied by drawings 3 wherein like parts are designated by like reference numerals.

In the drawings: 7 I

Figure 1 illustrates a complete receiving system embodying the features of the invention;

Figures 2, 3, and 4 are views showing details of the supports and of a prefered type of concentric line used in the system of Figure 1;Fig. 3a is a cross-section of Fig. 3 along the line 3Cb3l1, and shows the plates separated for a better view of the constructional details; 4

Figure 5 is a cross-sectional, partly schematic view showing a practical physical embodiment of the invention as applied to a receiving system of the type illustrated in Figure 1;

Figures 6 and '7 illustrate other types of concen- 5 tric lines which can be used in the practice of the present invention; and

Figure 8 shows a cross-sectional view, and Figure 8a a top plan view of a modification of the physical construction of the ultra-short radio wave receiver of Figure 1.

Referring to Figure 1 in more detail, there is shown a're'ceiver comprising two stages of radio frequency amplification and a detector. The tuned circuits of the receiver are shown as consisting of concentric lines comprising an outer conductor l and an inner conductor 2, the inner conductor being adjustable in its length within the outer conductor. The outer conductor comprises a cylindrical metallic pipe having two slots 3, 3 for enabling the input and output terminals to connect with the inner conductor 2 at any point along its length, in order to provide suitable impedance matching with the external circuits. For this purpose, the connections to the inner conductor 2 consist of tightly fitting rings 5, 5 over the outer surface of the inner conductor which are slideable along its length.

The first stage of radio frequency amplification is shown as consisting of a suitable input circuit, here designated, by way of example, as an antenna 4 which is connected through one of the slots 3 in the upper portion of the concentric line, but insulated from the outer conductor by virtue of a bead, not shown, or an air space between the sides of the slot and the connecting lead. The output circuit of the inner conductor includes a connection 6 (having in series therewith a condenser 40) which passes out of the concentric line through the other slot 3 to the input electrode of a suitable electron discharge device 1, preferably of the type known as the Acorn tube. It should be noted at this time that the two slots 3, 3 of this first tuned concentric line are at an angle of about with respect to each other on the periphery of the outer conductor, whereas the slots of the other tuned lines, to be discussed hereinafter, are on opposite sides of the line. This manner of cutting the slots for the first tuned circuit differently from the others is a matter of convenience inasmuch as it was desired thatthe antenna 4 extend vertically rather than in a line parallel to the connection 6. The antenna 4 may consist, in practice, of a rod about a foot or so in length when the length of the communication wave is about one meter or thereabouts.

Electron discharge device I is mounted in the center of a composite plate 8 extending in the vertical plane, which plate is adjustable in its position along the length of the concentric line by movement between two bars 9, 9 forming a channel therebetween, these bars contacting the outer surfaces of composite plate 8 and resting on a metallic base Ill which is at ground or zero radio frequency potential. The upper portion of the composite plate similarly moves between a pair of guide rods which areconnected to the supports II, II of the concentric line in a manner more completely shown in Figure 2, to be described later. The electrodes of the electron discharge device I connect with metallic plates located between the outer surfaces of the composite plate, but separated therefrom by mica insulators in order to form for these electrodes by-passing condensers to ground. The details of this composite plate are shown and described subsequently in connection with Figures 3 and 3a.

To obtain proper tuning of the tuned concentric line, the inner conductor may be moved bodily within the outer conductor, for coarse adjustment, and, for fine adjustment, a slight extension or retraction on one end of the inner conductor may be made by means of a screw and knob arrangement I2. A more detailed description of the adjustment of the inner conductor with respect to the outer conductor will be given later in connection with Figure '2.

The second stage of the radio frequency re- M ceiver of Figure 1 is essentially similar to that described above in connection with the first stage and includes the usual Acorn type of vacuum tube I mounted in its vertical adjustable composite plate 8, the input electrode to the second stage being connected to the inner conductor 2 of the second tuned concentric line by means of a ring 5 over the inner conductor and a connection I3 which extends within one of the slots 3 of the second concentric line, this last slot 3 being, as

i mentioned before, diametrically opposite to the other slot of this second concentric line.

The output electrode of the second stage is again connected to the tuned concentric line of the detector through a slot 3 in the third concentric line over a connection I4, the output lead of the third concentric line being coupled by a suitable connection I5 to an Acorn type of detector tube I6 from whose output electrode energy is passed to a suitable audio frequency amplifier and utilization circuit, not shown. Of course, connection I5 also extends through a slot in the concentric line from the inner conductor thereof to the detector tube.

By means of the arrangement shown in Figure 1, I am able to obtain the maximum gain permissible from the tuned concentric line, and the maximum selectivity consistent with such gain. This is because the slots enable the input and output leads to the rings 5 on the inner conductor to be moved substantially over the entire length.

of the inner conductor and to give any required spacing between the rings, while simultaneously the vacuum tube with its associated mounting can also be moved over the entire length of the concentric line to any position along the line so as to give minimum length of lead between Vacuum tube and concentric lines. As will be noted hereinafter, the lines themselves are adjustable over their supports or with their supports for obtaining the best location of contact of the line with the vacuum tube element, thus realizing minimum lead length. In elfect, the concentric line functions as an auto-transformer coupling element whose terminal connections are adjustable over the length of the auto-transformer.

By means of the connections on the tuned con-- centric circuit, depending upon whether the grid connection of the vacuum tube is nearer the open end of the concentric line than the plate connection, we obtain either step-up or step-down ratio of impedance transformation. In the event that the grid connection of the input tube has a lower input impedance than the output impedance of the previous tube, the connection to ring 5 for the input electrode of the tube will be at a lower point with respect to the closed end of the line than the other connection which feeds energy into the concentric line. Such an arrangement is illustrated in the first and second radio frequency stages of the receiver, Figure 1, while the third stage shows just the reverse because the input impedance of the detector circuit is greater than that of the output electrode of the second radio frequency stage. the ring 5 associated with the antenna 4 in the first stage, with respect to whether it should be on one side or the other of the other ring 5, depends upon the characteristics of the antenna circuit. Itwill be found that in some cases the antenna connection should go to the inner conductor on that side of the grid lead which is nearest the closed end of the concentric line. As a typical illustration of the positioning of the rings 5 it was found that when the receiver was operated at one meter in one particular embodiment, the ratio of the distances from the closed end to the ring 5 farthest removed from said closed end along the inner conductor to the distance from the same closed end to the ring 5 nearest this end was" of the order of 2 to 1.

Although Figure 1 shows the concentric lines and tubes removed somewhat from one another, it should be distinctly understood that this showing is merely for simplicity of illustration, since in practice the tube mountings and the lines will be as close as physically possible. In one particular embodiment the glass envelopes of the tubes 1, I and the detector I6 almost touched the outer conductors of the lines, the electrode connections to the lines thus being extremely short. Actually, in constructing an arrangement of the type shown in Figure 1, the concentric lines may, for greater convenience and minimum length of lead, be staggered with respect to one another, although this may not be necessary in all cases.

The method of supplying energy to the electrodes of the electron discharge devices I, 'I and I6 of the system of Figure 1 is described later in connection with Figure 5, which is a full size view of one embodiment tried out in practice.

Figure 2 shows in detail the method oi mounting a concentric line of the type shown in Figure 1, between a pair of upright metallic supports II these supports in turn being mounted on a horizontal metallic piece II, the latter being in contact with and movable over the metallic base plate II]. The movement of the entire line, the two supports II and the horizontal cross piece I! is efiected through the use of a slot I8 in the cross piece I! which, when the bolt and screw arrangement I9 is loosened, permits such adjustment. Each support has a substantially central hollow portion for accommodating the outer The position of conductor of the concentric line, and also a slot on one side of the support with a screw 20 extending through the flanged portions on opposite sides of the slot, but threaded only to the lower flanged portion. The use of the slots and the screws in the supports II, II is to enable the concentric line to be'moved with respect to the supports when the screws 20, 20 are loosened. When these screws, however, are tightened so as to securely fasten the concentric line to the supports H, the supports as a whole, together with the concentric line, can be moved over the base plate In by loosenin the screw l9.

At the upper end of each metallic support II there is provided a screw arrangement for fastening thereto one end of a metallic guide bar 2| which is adapted to bear against one side of the composite metallic plate 8 on the upper portion thereof, there being a similar metallic my guide rod 2! on the other surface of the composite plate 8 in a similar location, whereby the composite plate 8 is metallically connected to the base plate l0 both through the channel formed by the plates 9, 9 at the bottom of the composite plate and through the guide rods 2|.

For adjusting the effective length of the inner conduct-or of the concentric line, there is provided at one end of the concentric line a knurled knob and screw arrangement l2 and also a screw l3 which protrudes through the outer conductor I and securely fastens the inner conductor l2 in position. Before proceeding to describe the adjustment of the inner conductor, it should be noted that said inner conductor tube consists in effect, at the adjustable end, of a. slotted metal plug which substantially covers the entire inner area of the outer conductor for a very short section near the closed end, this plug having an aperture therein for enabling the inner conductor to extend from the knob and screw arrangement l2 towards the open end of the line. A coarse adjustment of the concentric line is accomplished by loosening screw l3 and bodily moving the inner conductor including the screw and knob arrangement 12. When the screw I3 is securely fastened to the inner conductor 2, a Vernier adjustment is obtainable by movement of the screw and knob arrangement l2 which enables movement of an inner length of rod 22 7 extending within the inner conductor fitted snugly therein, and protruding slightly from the open end of the inner conductor. In one embodiment used in practice, the protrusion of the rod 22 was to the extent of one inch from the free end of the inner conductor 2.

Figure 3 shows in more detail the manner of construction of the composite plate 8. This plate, as will be more readily observed from an inspection of Figure 3a which shows a crosssectional view of a portion of the plate along the lines 3a-3a, comprises two outer metallic composite plates 23, 23, which have adjacent each other suitable insulating spacers such as mica sheets 24, there being provided between the mica sheets physically separated small metallic plates 25, these in turn being connected to the electrodes of the vacuum tube and being provided with terminals extending to the edges of the composite plate for connection with the associated circuit elements. Figure 3a shows these plates separated for the sake of illustration, although in practice the entire composite plate when screwed together by screws 26 has a thickness only slightly greater than one-eighth of an inch. The inner metallic sections 25 are provided with holes to enable the screws 26 to pass therethrough for clamping the assembly together without conductively connecting the outer plates 23 to the inner plates.

Figure 3 illustrates four of these plates 25 in dotted lines, each of the plates being connected at one point to an electrode of its associated vacuum tube 1, and at another point to a suitable terminal. The composite plate 8 is arranged in a vertical position and is slideable in a channel provided by the small rectangular bars 3 to any position along the length of the bars 9, in order to provide minimum lead length connection to the concentric lines which are adapted to be mounted on both sides of the composite plate. A suitable aperture 44 substantially in the center of the composite plate 8 accommodates the Acorn tube 1. It will thus be apparent that each metallic plate 25 forms one plate of a condenser whose other plates are the outer surface 23 of the composite assembly 8, which outer surfaces are at ground or new radio 'frequency potential. Thus the electrodes of the vacuum tube 1 which are connected to the plates 25 and their connections are by-passed to ground.

Figure 4 illustrates the mounting for the detector Acorn. tube It of Figure l, and consists essentially of a vertically arranged block of metal 2! of rectangular shape provided at its center trode of the detector Acorn tube, the lower terminal being conncted to the associated. ex-' ternal circuit. The block thus provides a plurality of by'-pass condensers for the electrodes of the detector tubes in the same way that the composite plate 8 provides by-pass condensers for the electrodes'of the acorn tube 7.

Figure 5 is a partly schematic cross-sectional view of a practical embodiment of a receiver system built along the lines of Figure 1. This crosssectional view is substantially full size, and is given for the purpose of more clearly showing the manner in which the elements of the receiver system are mounted to give an extremely compact assembly. It should be noted that the connecting leads 6, I3, l4 and I5 extending between the concentric lines I, 2; I, 2 and the Acorn tube electrodes are of minimum length. The leads 6,13 and I5 between the control electrodes of the acorn tubes 1 and I6 and the inner conductors 2 of the respective tuned concentric lines include in series therewith a suitable blocking condenser 40 for the purpose of isolating the plate supply voltages from the grids of the tubes. These condensers 40, 4!! are preferably located; within the outer conductor I of the concentric line and consist of very compact mica condensers approximately one-eighth of an inch square. Suitable negative grid biasing poten tials are applied to the control grids of the tubes through lead connections labeled C. In practice, the anode supply labeled +3 for the first and second radio frequency stages comprising tubes 1, '1 was connected to the plate III, while the anode supply labeled +3 for the detector tube !6 was directly connected to the electrode of the tube through one of the plates 28 on the metallic block 21,

Figure 6 is a modification of the concentric lines shown in Figures 1, 2, and and diiiers therefrom only in the provision of outer con.- ductor 4| which is substantially LJ--shaped, as shown, instead of completely surrounding the inner conductor. One side of the U conductor 4|, preferably the upper side, is open, While the sides thereof may have usual slots provided for in the concentric lines of l. and 5. The same method of adjusting the inner and outer conductors of the U with respect to one another and with respect to the other elements of the circuit heretofore described applies to this figure also.

Figure 7 shows another modification of the concentric line which is in the form of a coil All! for conserving space. This coil. 42 may be provided with slots which extend continuously from one end. to the other, or with a plurality of separated slots 43 in the manner shown in order to provide access to the inner conductor. Where a plurality of coiled concentric lines, of the ty 39 shown in this figure, are to be used in the system. like Figure l the coils would be located in plan i which are substantially parallel to one another, the vacuum tubes being located between the coils.

It is to be distinctly understood that the invention is not limited to the precise arrangements shown in the drawings since various modifications thereof may be made Without departing from the spirit and scope thereof. For example, the outer conductor of the concentric line need not be cylindrical or U shaped, but instead may consist of any suitable cam arrangement which surrounds the conductor on substantially all sides except perhaps the bottom, the bottom portion of the outer conductor comprising the grounded plate. It should also be understood that the features of the invention are not limited to receivers since they are similarly applicable to transmitting circuits.

Figures 8 and 8a show a modification of the system of Figure 1, Figure 8 being a partly sche matic cross-sectional view of a receiving arrangement, and Figure 8a a top plane View of such an arrangement. In this last modification, the outer conductors merely consist of partitions 33 which serve the dual purpose of separating the inner conductors from one another and as composite plates for supporting the vacuum. tubes and by-passing radio frequency currents from their electrodes to ground. In Figures 8 and 8a, there are shown a plurality of radio frequency stages comprising amplifier tubes 1', i, and a detector tube IS, the inner conductors being designated by the numeral 2 and the outer conductors consisting of the top and bottom plates St, 3 3 forming the sides of a relatively long, fiat, rectangularly-shaped box. Partitions and composite plate 33 are designed to be of sufficient length so that they contact both ends of the box in the manner shown in Figure 8a during adjustment or movement. The various by-passing condensers, leads to the batteries and various resistors are not shown for the purpose of simplicity. Such details are Well known and may follow the teachings described above in connection with the description of Figure 1.

What is claimed is:

1. Ultra short wave apparatus comprising an electron discharge device having an input electrode and an output electrode, an input circuit comprising a tuned section of concentric line and an output circuit comprising another tuned section of concentric line parallel to said first section, each of said sections of line having a slot in the outer conductor along the length thereof for enabling a connection to the inner conductor at various points throughout its length, said device being located between said tuned circuits and having said input electrode coupled to the inner conductor of said input circuit and said output electrode coupled to the inner conductor of said output circuit, whereby the lengths of the connections between input and output circuits and said device are a minimum.

2. Ultra short wave apparatus comprising an electron discharge device having an input electrode and an output electrode, an input circuit comprising a tuned section of concentric line and I an output circuit comprising another tuned section of concentric line parallel to said first section, each of said sections of line having a slot in the outer conductor along the length thereof for enabling a connection to the inner conductor at various points throughout its length, said device being located between said tuned circuits and having said input electrode coupled to the inner conductor of said input circuit and said output electrode coupled to the inner conductor of said output circuit, and an adjustable mounting for each section of concentric line for enabling said lines to be moved relative to each other in the direction of their axes, whereby the lengths of the connections between input and output circuits and said device are a minimum.

3. Ultra short wave apparatus comprising an electron discharge device having an input electrode and an output electrode, an input circuit comprising a tuned section of concentric line and an output circuit comprising another tuned section of concentric line parallel to said first section, each of said sections of line having a slot in the outer conductor along he length thereof for enabling a connection to the inner conductor at various points throughout its length, the slots in the outer conductors of both sections of line being parallel to each other, said device being located between said tuned circuits and having said input electrode coupled to the inner conductor of said input circuit and said output electrode coupled to the inner conductor of said output circuit, and a support for mounting said device, said support comprising a composite plate in the vertical plane which is movable in position relative to said sections of concentric line, whereby the lengths of the connections between input and output circuits and said device are a minimum.

4. Ultra short wave apparatus comprising an v having said input electrode coupled to the inner conductor of said input circuit and said output electrode coupled to the inner conductor of said output circuit, a support for said device, said support comprising a composite plate in the vertical plane which is movable in a position relaprising a plurality of parallel concentric conductive to and in a direction parallel to the axes of said sections of concentric line, and an adjustable mounting for each section of concentric line for enabling said lines to be moved relative-to each other in the direction of their axes, whereby the lengths of the connections between input and output circuits and said device are a minimum.

5. A multi-stage short wave radio frequency amplifier comprising a plurality of parallel sections of tuned concentric lines, each of said-concentric lines having an inner and an outer conductor, and an electron discharge device located between each two adjacent sections of line intermediate the ends thereof and coupled to the inner conductors thereof, whereby the lengths of connections between each device and its associated lines are a minimum.

' 6. A multi-stage amplifier in accordance with claim 5, characterized in this that said concentric lines are located substantially in a single plane, the outer conductor of each line having a slot in the length thereof for enabling connection between an electron discharge device and the inner conductor.

7. A multi-stage amplifier comprising a plurality of parallel sections of tuned concentric lines, and an electron discharge device located between each two adjacent sections of line and coupled thereto, whereby the lengths of the connections between each device and its associated lines are a minimum.

8. An ultra short wave receiver comprising a source of high frequency energy, a concentric line having an inner and an outer conductor, said outer conductor having at least two spaced parallel slots along the length thereof for enabling connection to the inner conductor, means for coupling said source to said inner conductor through one of said slots, another concentric line also having two spaced parallel slots in the outer conductor, an amplifier tube located between said lines intermediate their ends, a connection from said first line through said other slot and a connection from said second line through a slot each to a different electrode of said tube, and a utilization circuit coupled to the inner conductor of said second line through the other slot thereof.

9. A multi-stage amplifier comprising a plurality of parallel sections of tuned concentric lines, means for tuning each line from one end thereof, and an electron discharge device located between each two adjacent sections of line and coupled to the inner conductors thereof by the shortest possible leads between the device and inner conductor, whereby the lengths of the con nections between each device and its associated lines are a minimum.

10. A multi-stage short wave radio frequency amplifier comprising a plurality of parallel sections of tuned concentric lines, each of said concentric lines having an inner and an outer con.- ductor, and an electron discharge device located between each two adjacent sections of line intermediate the ends thereof and coupled to the inner conductors thereof, over substantially the shortest possible paths, whereby the lengths of connections between each device and its associated lines are a minimum.

11. A multi-stage short wave amplifier com tor lines placed side by side, adjacent lines having a common separating wall, and an electron discharge device supported by the common wall of each two adjacent lines and having an input electrode coupled to the inner conductor of one line and an output electrode coupled to the inner conductor of the adjacent line between which it is supported.

12. A multi-stage amplifier in accordance with claim 5, characterized in this that said outer conductors of said lines are substantially square. in shape, there being a common wall between adjacently locatedlines. 13. A multi-stage amplifier in accordance with claim 5, characterized in this that said outer conductors of said lines are substantially cylindrical in shape, said devices being located between outer conductors.

14. A tuned circuit comprising a concentric line having an inner and an outer conductor, means for supporting said inner conductor from said outer conductor, said inner conductor having a sliding fit in said outerconductor for obtaining a coarse adjustment of the tuning of said line, and a screw arrangement for changing the length of said inner conductor within said outer conductor 1 for obtaining a finer adjustment of tuning of said line.

15. A tuned circuit comprising a section of concentric line having an inner and an outer conductor, said outer conductor having at least one slot extending over an appreciable portion of the length thereof for enabling access to said inner conductor over the length of said slot,

. 16. A tuned circuit comprising a section of concentric line having an inner and an outer conductor, said outerconductor having at least one slot extending over an appreciable portion of the length thereof for enabling access to said inner conductor over the length of said slot, and a plurality of metallic rings engaging said inner conductor and movable over the length thereof for providing circuit connections for said inner conductor.

1'7. A multistage ultra high radio frequency amplifier with tuned concentric transmission lines as coupling impedances between stages, each of said lines having means in the interior of said lines for varying the effective length thereof with the longest axis of each line parallel to the longest axis of the other lines, whereby the wiring to the various tube elements is reduced to a minimum.

18. A multistage ultra high radio frequency amplifier with tuned variable length concentric transmission lines as coupling impedances between stages, each of said lines having means for varying the actual length of the inner conductor thereof, with the longest axis of each line parallel to the longest axis of the other lines, whereby the wiring to the various tube elements is reduced to a minimum.

19. In a multistage ultra high radio frequency amplifier with each stage having an input and output circuit, the combination of concentric transmission lines as interstage coupling impedances consisting in each interstage of a concentric transmission line comprising an outer grounded tube and an inner concentric tube with the longest axis of each inner tube parallel to the longest axes of the other inner tubes, tuning means associated with each inner tube and movable along its length, additional means associated with each inner tube for supplying the input and output circuits of each of said amplifier stages with the proper direct current voltages, whereby the wiring to each of said input and output circuits is reduced to a minimum.

20. A multistage ultra high radio frequency amplifier with plunger type tuned concentric transmission lines as coupling impedances'between stages, with the longest axis of each line parallel to the longest axis of the other lines, whereby the wiring to the various tube elements is reduced to a minimum.

21. A multistage ultra high radio frequency amplifier with plunger type tuned variable length concentric transmission lines as coupling impedances between stages with the longest axis of each line parallel to-the longest axis of the other lines, whereby the wiring to the various tube elements is reduced to a minimum.

22. In a multistage ultra high radio frequency amplifier with each stage having an input and output circuit, the combination of concentric transmission lines as interstage coupling impedances consisting in each interstage of a con centric transmission line comprising an outer grounded tube and an inner concentric tube with the longest axis of each inner tube parallel to the longest axes of the other inner tubes, plunger type tuning means associated with each inner tube and movable along its length, additional means associated with each inner tube for supplying the input and output circuits of each of said amplifier stages with the proper direct current voltages, whereby the wiring to each of said input and output circuits is reduced to a minimum.

23. In a multistage ultra high radio frequency amplifier with input and output circuits, and with a single concentric transmission line as the only coupling impedance between stages consisting of an outer tubular grounded conductor and an inner concentric tubular conductor, an additional concentric transmission line consisting of an outer tubular grounded conductor and an inner concentric tubular conductor and associated with the input circuit to said amplifier, a movable means connected to an antenna and connected with and movable along the inner conductor of said additional concentric transmission line for matching the antenna impedance to that of the input circuit of said amplifier such that the input circuit is held at a high ultra radio frequency potential.

24. In a multistage ultra high radio frequency amplifier with input and output circuits, and with l a single concentric transmission line as the only coupling impedance between stages consisting of an outer tubular grounded conductor and an inner concentric tubular conductor, an additional concentric transmission line consisting of an outer tubular grounded conductor and an inner concentric tubular conductor and associated with the input circuit to said amplifier, a movable means connected to an antenna and connected with and movable along the inner conductor of said additional concentric transmission line for matching the antenna impedance to that of the input circuit of said amplifier, and'tuning means associated with each interstage concentric transmission line and with said additional concentric transmission line for varying their electrical length. r

25. Ultra short wave apparatus comprising a source of high frequency energy, a first tuned circuit in the form of a coaxial line having an inner and an outer conductor, means for coupling said source to said inner conductor, a second tuned circuit in the form of acoaXial line having an inner conductor and'an outer conductor, an amplifier electron discharge device having an inputelectrode and an output electrode, means coupling said input electrode to the inner conductorof said first coaxial line, means coupling said output electrode to the inner conductor of said second coaxial line, and a utilization circuit also coupled to the inner conductor of said second coaxial line. i

26. Ultra short wave apparatus comprising a source of high frequency energy, a first tuned circuit in the form of a coaxial line having an inner and an outer conductor, means for coupling said source to said inner conductor at one point intermediate itsends, a second tuned circuit in the form or a coaxial line'having an inner conductor and an outer conductor, an amplifier electron discharge device having an input electrode and an output electrode, means coupling said input electrode to the inner con-ductor of said first coaxial line at another point intermediatel its ends, means coupling said output electrode to the inner conductor of said second coaxial line at a point intermediate its ends, and a utilization circuit also coupled to the inner conductor of said second coaxial line at another point intermediate its ends.

27. Ultra short wave apparatus comprising a source of high frequency energy, a first tuned circuit in the form of-a coaxial line having an inner and outer conductor, cans for coupling said source to said inner conductor, a second tuned circuit in the form of a coaxial line having an inner conductor and an outer conductor, an amplifier electron discharge device having an input electrode and an output electrode, means coupling said input electrode to the inner conductor of said first coaxial line, means coupling said output electrode to the inner conductor of said second coaxial line, and a utilization circuit also coupled to the inner conductor of said second coaxial line, all of said means being adjustable in position over the respective lengths of said inner conductors.

28. In a multistage ultra high radio frequency amplifier having two stages with input and output circuits, and with a single concentric transmission line as the only coupling impedence between said two stages consisting of an outer tubular T grounded conductor and an inner concentric tubular conductor, an additional concentric transmission line consisting of an outer tubular grounded conductor and aninner concentric tubular conductor and associated with the input circuit to said amplifier, a movable means connected to an antenna and connected with and movable along the inner conductor of said additional con-centric transmission line for matching the antenna impedance to that of the input circuit of the first stage of said amplifier, and movable means connected to the output electrode of said first stage and the input electrode of the second stage and movable along the inner conductor of said single concentric transmission line for matching the impedance of the output circuit of the first stage to that of the input circuit of the second stage, and tuning means associated with each concentric transmission line for varying their electrical length.

- PAUL D. ZO'I'IU. 

